/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2011-2013, University of Amsterdam
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
:- module(base32,
[ base32/2, % ?PlainText, ?Encoded
base32//1 % ?PlainText
]).
/** <module> Base32 encoding and decoding
Prolog-based base32 encoding using DCG rules. Encoding according to
rfc4648.
For example:
==
1 ?- base32('Hello World', X).
X = 'JBSWY3DPEBLW64TMMQ======'
Yes
2 ?- base32(H, 'JBSWY3DPEBLW64TMMQ======').
H = 'Hello World'
==
@see http://en.wikipedia.org/wiki/Base32
@author Jan Wielemaker
*/
%! base32(+Plain, -Encoded) is det.
%! base32(-Plain, +Encoded) is det.
%
% Translates between plaintext and base32 encoded atom or string.
% See also base32//1.
base32(Plain, Encoded) :-
nonvar(Plain),
!,
atom_codes(Plain, PlainCodes),
phrase(base32(PlainCodes), EncCodes),
atom_codes(Encoded, EncCodes).
base32(Plain, Encoded) :-
nonvar(Encoded),
!,
atom_codes(Encoded, EncCodes),
phrase(base32(PlainCodes), EncCodes),
atom_codes(Plain, PlainCodes).
base32(_, _) :-
throw(error(instantiation_error, _)).
%! base32(+PlainText)// is det.
%! base32(-PlainText)// is det.
%
% Encode/decode list of character codes using _base32_. See also
% base32/2.
base32(Input) -->
{ nonvar(Input) },
!,
encode(Input).
base32(Output) -->
decode(Output).
/*******************************
* ENCODING *
*******************************/
encode([I0, I1, I2, I3, I4|Rest]) -->
!,
[O0, O1, O2, O3, O4, O5, O6, O7],
{ A is (I0<<32)+(I1<<24)+(I2<<16)+(I3<<8)+I4,
O00 is (A>>35) /\ 0x1f,
O01 is (A>>30) /\ 0x1f,
O02 is (A>>25) /\ 0x1f,
O03 is (A>>20) /\ 0x1f,
O04 is (A>>15) /\ 0x1f,
O05 is (A>>10) /\ 0x1f,
O06 is (A>>5) /\ 0x1f,
O07 is A /\ 0x1f,
base32_char(O00, O0),
base32_char(O01, O1),
base32_char(O02, O2),
base32_char(O03, O3),
base32_char(O04, O4),
base32_char(O05, O5),
base32_char(O06, O6),
base32_char(O07, O7)
},
encode(Rest).
encode([I0, I1, I2, I3]) -->
!,
[O0, O1, O2, O3, O4, O5, O6, 0'=],
{ A is (I0<<32)+(I1<<24)+(I2<<16)+(I3<<8),
O00 is (A>>35) /\ 0x1f,
O01 is (A>>30) /\ 0x1f,
O02 is (A>>25) /\ 0x1f,
O03 is (A>>20) /\ 0x1f,
O04 is (A>>15) /\ 0x1f,
O05 is (A>>10) /\ 0x1f,
O06 is (A>>5) /\ 0x1f,
base32_char(O00, O0),
base32_char(O01, O1),
base32_char(O02, O2),
base32_char(O03, O3),
base32_char(O04, O4),
base32_char(O05, O5),
base32_char(O06, O6)
}.
encode([I0, I1, I2]) -->
!,
[O0, O1, O2, O3, O4, 0'=, 0'=, 0'=],
{ A is (I0<<32)+(I1<<24)+(I2<<16),
O00 is (A>>35) /\ 0x1f,
O01 is (A>>30) /\ 0x1f,
O02 is (A>>25) /\ 0x1f,
O03 is (A>>20) /\ 0x1f,
O04 is (A>>15) /\ 0x1f,
base32_char(O00, O0),
base32_char(O01, O1),
base32_char(O02, O2),
base32_char(O03, O3),
base32_char(O04, O4)
}.
encode([I0, I1]) -->
!,
[O0, O1, O2, O3, 0'=, 0'=, 0'=, 0'=],
{ A is (I0<<32)+(I1<<24),
O00 is (A>>35) /\ 0x1f,
O01 is (A>>30) /\ 0x1f,
O02 is (A>>25) /\ 0x1f,
O03 is (A>>20) /\ 0x1f,
base32_char(O00, O0),
base32_char(O01, O1),
base32_char(O02, O2),
base32_char(O03, O3)
}.
encode([I0]) -->
!,
[O0, O1, 0'=, 0'=, 0'=, 0'=, 0'=, 0'=],
{ A is (I0<<32),
O00 is (A>>35) /\ 0x1f,
O01 is (A>>30) /\ 0x1f,
base32_char(O00, O0),
base32_char(O01, O1)
}.
encode([]) -->
[].
/*******************************
* DECODE *
*******************************/
decode(Text) -->
[C0, C1, C2, C3, C4, C5, C6, C7],
!,
{ base32_char(B0, C0),
base32_char(B1, C1)
},
!,
{ C7 == 0'=
-> ( C6 == 0'=, C5 == 0'=
-> ( C4 == 0'=
-> ( C3 = 0'=, C2 = 0'=
-> A is (B0<<35) + (B1<<30),
I0 is (A>>32) /\ 0xff,
Text = [I0|Rest]
; base32_char(B2, C2),
base32_char(B3, C3),
base32_char(B4, C4),
A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) + (B4<<15),
I0 is (A>>32) /\ 0xff,
I1 is (A>>24) /\ 0xff,
Text = [I0,I1|Rest]
)
; base32_char(B2, C2),
base32_char(B3, C3),
base32_char(B4, C4),
base32_char(B5, C5),
A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) +
(B4<<15) + (B5<<10),
I0 is (A>>32) /\ 0xff,
I1 is (A>>24) /\ 0xff,
I2 is (A>>16) /\ 0xff,
Text = [I0,I1,I2|Rest]
)
; base32_char(B2, C2),
base32_char(B3, C3),
base32_char(B4, C4),
base32_char(B5, C5),
base32_char(B6, C6)
-> A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) +
(B4<<15) + (B5<<10) + (B6<<5),
I0 is (A>>32) /\ 0xff,
I1 is (A>>24) /\ 0xff,
I2 is (A>>16) /\ 0xff,
I3 is (A>>8) /\ 0xff,
Text = [I0,I1,I2,I3|Rest]
)
; base32_char(B2, C2),
base32_char(B3, C3),
base32_char(B4, C4),
base32_char(B5, C5),
base32_char(B6, C6),
base32_char(B7, C7)
-> A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) +
(B4<<15) + (B5<<10) + (B6<<5) + B7,
I0 is (A>>32) /\ 0xff,
I1 is (A>>24) /\ 0xff,
I2 is (A>>16) /\ 0xff,
I3 is (A>>8) /\ 0xff,
I4 is A /\ 0xff,
Text = [I0,I1,I2,I3,I4|Rest]
},
decode(Rest).
decode([]) -->
[].
/*******************************
* BASIC CHARACTER ENCODING *
*******************************/
base32_char(00, 0'A).
base32_char(01, 0'B).
base32_char(02, 0'C).
base32_char(03, 0'D).
base32_char(04, 0'E).
base32_char(05, 0'F).
base32_char(06, 0'G).
base32_char(07, 0'H).
base32_char(08, 0'I).
base32_char(09, 0'J).
base32_char(10, 0'K).
base32_char(11, 0'L).
base32_char(12, 0'M).
base32_char(13, 0'N).
base32_char(14, 0'O).
base32_char(15, 0'P).
base32_char(16, 0'Q).
base32_char(17, 0'R).
base32_char(18, 0'S).
base32_char(19, 0'T).
base32_char(20, 0'U).
base32_char(21, 0'V).
base32_char(22, 0'W).
base32_char(23, 0'X).
base32_char(24, 0'Y).
base32_char(25, 0'Z).
base32_char(26, 0'2).
base32_char(27, 0'3).
base32_char(28, 0'4).
base32_char(29, 0'5).
base32_char(30, 0'6).
base32_char(31, 0'7).